EMT2455 Data Communications

Instructor: Dr. X. Li

Email: xhli@citytech.cuny.edu

Office Hours: See announcement on the Blackboard.

Note: with the waning of COVID, the office hours have been back to in-person.

Welcome to EMT2455 Data Communications, one of the fundamental courses to computer networks. This webpage can simply be reached by googling “City Tech EMT2455 Dr. Li”.

Course Description

Fundamentals of data communications and computer networks protocols and standards. It provides a basic understanding of data communication systems with practical examples of communication networks as applied in engineering technology. Study of OSI and TCP/IP models, data transmissions, multiplexing, transmission media, channel capacity, bandwidth utilization, network topologies, network cabling system, IP addressing, local area networks (LANs), wide area networks (WANs), and wireless network. Students carry out experiments using modern hardware and software networking tools.

Syllabus and Grading PolicY

Items Percentage
Midterm Exam
Final Exam & Extra Credits

A: 93~100     A-: 90~92.99     B+: 87~89.99   B: 83~86.99 B-: 80~82.99     C+: 77~79.99     C: 70~76.99       D: 60~69.99

Course Documents

  • Course Syllabus: Detailed information about the course and course policies, including requisites, textbook, grading policy, and other course policies.
  • Lab Reports Requirements: Detailed requirements on lab experiments and lab reports (including report’s content and format).
  • Guide on How to Write Technical Reports: A very good guide written by IET (Institute of Engineering & Technology, one of the largest international non-for-profit engineering professional organizations, dated back to 1871).
  • User Guide of the Crimp Tool: The simple user guide that come with the crimp tool we used in the class.

Weekly Schedule

Class# Topics Slides/Handouts Others
Intro to Course and course syllabus
Ch 1. Intro to Computer Networks and history of the Internet, ISO OSI and TCP/IP models, service structures, packet switching, and encapsulation
4, 5
Ch 2-1. Network topology, multiplexing, transmission media, fiber optical communication, wireless computer network, IEEE802.11, structural cabling system, devices for home LAN/WLAN

Quiz 1

Ch 2-2. Internet Backbone
Ch 2-3. Submarine Communications Cables
Ch 2-4. Data and signal, frequency domain analysis, signal transmission, bandwidth, modulation, baseband & broadband, Nyquist bit rate, Shannon capacity

Midterm Exam

HW2 & 3 Presentations
10, 11
Ch 3. Data Link Layer: Ethernet, IEEE802.3, CSMA/CD protocol, Ethernet frame, CRC, MAC address, 10Base-T/100Base-T, Gigabit Ethernets

Lab 1: Introduction to Packet Analyzer
Ch 3 (contd). Ethernet cables

Lab 2: Building an Ethernet cable
Quiz 2

Ch 4. Network Layer -- ARP, IPv4 addressing

Lab 4: ARP
BYOD next class
Lab 3: WLAN Site Survey
Final Exam

*Lab3 (NYCCT WLAN Site Survey) Materials:

Lab software

  • WireShark:   It is a free, and one of the most popular packet/protocol analyzer software. It supports Linux, OS X, BSD, Solaris, and Microsoft Windows.  https://www.wireshark.org/download.html
  •  Capsa Free by ColaSoft:  Free, but registration is required! Runs on Windows only.    http://www.colasoft.com/capsa-free/
  • OPNET:   One of the most popular commercial computer networks modeling, simulation and performance management software. OPNET Modeler has an academic edition available:  https://enterprise37.opnet.com/4dcgi/SIGNUP_NewUserOther
  • ns-2:   The very powerful and advanced network simulator widely used in research and high-ed teaching.  It is open-source. It runs on GNU/Linux, FreeBSD, Solaris, Mac OS X and Windows that support Cygwin. One needs to know scripting language, queuing theory and modelling techniques to use it.  ns-2 (build of 2009) is not actively maintained any more.
  • ns-3:   Descendant of the very famous ns-2. Advanced and complex as ns-2, but unfortunately not backward compatible with ns-2.  Just like ns-2, ns-3 has no GUI and requires very considerable time to learn and use.   http://www.nsnam.org/


  • Open Lab is Available!  Please be advised that effective from the 5th Thursday of this semester, open lab will be available in room V606, V608 and V613. You are welcome to use these lab rooms and equipment there to work on your projects or lab experiments. Open Lab hours are: Thursdays 11:20AM-2:00PM. See department secretary for details.
  •  More to be announced.

Archived Announcements

  • Summer Intern Opportunities:   Brooklyn Navy Yard had direct collaboration with our College and hired many of our City Tech students in the past as summer interns. The internship program in Brooklyn Navy Yard is open to accept applications. A variety of intern positions are offered by the companies inside Brooklyn Navy Yard.  Check details by clicking the link:  https://brooklynnavyyard.org/employment/summer-internship/
  • Brooklyn Tech Triangle U is back!  The Be.In Symposium (formerly known as “Brooklyn Tech Triangle U” is back in this April! It features a series of exciting events, panels, networking events that bring together the technology, digit media andeducation community from Downtown Brooklyn, DUMBO and BNY. See http://beinbrooklyn.org/symposium/ for details.
  • NJ Tech Council IoT Conference 2017 on April 26, 2017: The annual NJ Tech Council IoT Conference 2017 will feature AWS IoT cloud and AT&T foundry, Smart City, smart transportation, many IoT projects demo and networking reception. It will be hold at Steven Insititution of Technology, Hoboken, NJ, on April 26, 2017. If interested, please contact Dr. Li for free-registration promotion code by April 12. See the link here for detailed conference agenda.
  • Brooklyn Tech Triangle Technology Company Tour  is scheduled on Friday, April 8, 2016. See the Blackboard for details.
  • Good news: Schneider Electric is Hiring! Schneider Electric is one of the leading companies in the fields of energy managment and infrastruture equipments all over the global. It has several different openning, both full-time and part-time. They come to our campus to recruit. You are highly suggested to attend their info session on March 3, 2015, 1-2PM, at room N402. They will come back on March 19 for interviewing. Please see CET Dept. Secretary for more details!
  • Brooklyn Tech Triangle U: A series of events to connect the Tech+Arts+Academic communities in Brooklyn MetroTech, DUMBO and Brooklyn Navy Yard. Career events on March 5 and 6, 2015: http://brooklyntechtriangle.com/tech-u/#career-events
  • MobileWeek NY 2015 Hiring Mixer: Join the official MobileWeek Hiring Mixer hosted at Yelp! Which is free for all developers and designers! Date: April 21, 2015, 5:30 PM – 8:30 PM, Venue: YELP! Office NYC | 11 Madison Ave, 16th Floor, New York, NY 10010   See MobileWeek official website for details:   http://mobileweek.co/hiring/